Portable test unit for a non-contacting pickup utilizing a rotating swash surface and means to adjust the pickup relative thereto



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aired States @arent PORTABLE TEST UNTI' FOR A NON-CONTACITNG u tnt. cr.con .e5/oo Us. cr. 324-34 ABSTRACT 0F THE DISCLOSURE A portable testunit for field testing and calibrating noncontact pickups. Such testunits include a rotatable swashsurface. The present invention providesmeans for adjustinga pickup to position the sensing tip thereofaccurately relative to the swash-`surface.

BACKGROUND 0F THE INVENTION Field of theinvention .v

reinvention relates t0 portable test unie for neta testing noncontactpickups,

Description of the prior art Portable test units are available for eldtesting non contact pickups to determine their output characteristic;Such test units nclpde a static tast assembly and a dynamic testassembly.

In the dynamic test assembly, the pickup is supported vertically withits sensing tip spaced-apart -from the swashsurface of a rotatablesubjacent plate member. When the plate member is rotated, theswasheurface simulates a vibrating metallic body wherein the magnitudeof vibration is known. The magnitude of vertical displacements of thesvvasl't-suroe varies from a maximum at the rim to zero at the center.The location of a pickup tip along tbe diameter determines the precisedisplacement between zero and the maximum value; Prior art-test unitsinclude bori- -zontaladjustment means for moving the pickup trans;

distance. In t'ne prior art test units, such adjustment has beenlaboriously accomplished by manually raising and lowering the pickup.

SUMMARY OF THE Schiene' pickup equals the static output voltage for thedesired gap I .l 2 n A v Still another object of this invention is toprovide a. portable test unit by which non-contact pickups may beaccurately calibrated in the held.

The present invgntion provides an improved portable test unit for eldtesting. and calibrating non-contact pick ups. The present improvementresides in the dynamic test assembly which includes a plate memberhaving a swashsurface and a rotation axis. Die swash-surface is inclinedrelative to a reference plane extending normal to tbe rotztion axis` Thereference plane intersects the swash-surface along a line whichintersects the rotation axis. Means i! provided for supporting the platemember for rotation about the rotation axis. Mounting means pports a noncontact pickup with the sensing tip thereof spaced-apart from theswa'sb-surface. Transverse adjustment mean'sper. Y

mits moving the means transversely to position the sensing tipaccurately at a selected location along a radius 0f the swash-surface.Drive means including speed adjustment' means is provided for rotatingthe plate member at a selected velocity. Y i

In accordance-with the present invention, gap distance adjustment meansis provided for moving the pickup para).

lel to the rotation axis to position the sensing tip thereof accuratelyat a predetermined distance frou the reference plane. In the preferredarrangement, the gap distance adjustment means is interposed between themounting means and the transverse adjustment means whereby the pickupand the mounting means are moved as a unit.

BRIEF DEsCRIPnoN 0F THE DRAWINGS.

FIG. 3 is a plan view of a portable test unit incorporating the gapdistance adjustment of this invention:

FIG. 4 is a crossfsection view taken along the lined-4 of FIG. 3;

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 3; and

FIG. 6 is a side view of a rotatable plate member, sche--A maticallyillustrating' the position of the pickup relative to the wash-surface ofthe plate member. DEscam'roN or ma PREFERRED EMBODDAENIS'rrosuaiiazareprpydedwsetfonhtsenment 'i non-contara pickups and theirtypical uses.

PIG. l illustrates a bearing housing 19 provided with an interior bronzebushing 12, having a bushing opening l 13. The side wall of the bearinghousing l is provided 'me principal object of this imitation' is toprovide an improved portable test unit for field testing non-contactPickups- Another object of this invention' is to provide an improvedportable test 'unit of the. type described wherein the sensing tip ofthe pickup being tested may be readily and accurately positioned at aknown static .ap distance iromtheswash-surface.' s

with an opening 14 communicating with the bushing opening 13. Theconductive pickup head or sensing tip 16 of n l non-contact pickup 18 isintroduced into the opening 14 f and is secured to the bearing housing10 by means not shown. A shaft 20 is rotatably supported by the bushingi 12. When the shaft- 20 rotates, 'it may wobble within the bushing 12as a result of mass eccentricity, shaft misaligxk ment, worn bearingsand other reasons. The pickup 18 is intended to detect movement of theshaft 20 relative to the sensingtip 16. v

j 3,539,912 .Patented No'vgto, :sin

' vibration signal having a frequency corresponding to the frequency ofthe shaft rotation and an amplitude which varies s a function of thepeak-tirpeak'displacernent'of t the shaft.

E ach pickup develops a characteristic output voltage per unit ofdisplacement at a known static gap distance.

A portable test unit 26 for testing non-contact pickups is in the lieldas illustrated in FIGS. 3-6, inclusive. The test unit 26 includes staticand dynamic test assemblies 28, 30. The test unit 26 includes anenclosure 32 having a lid (not shown) and interior partitions 34supporting a top wall 36. I

, STA'I'IC TEST ASSEMBLY Referring to FIG. 3, the static test assembly28 typically comprises a support 38 adapted to receive a split bodyadaptor bushing 39 carrying the pickup 18. The sensing tip 16 ispositioned opposite a metal pad 40 of a microm- 'eter 42. The pickup 13is connected through the oscillator 26 vto a voltmeter 44 of the typecapable of readingdirect current and alternating current voltages. Thestatic gap output voltage Vo--the direct current component of the outputsignal-as indicated by the voltmeter 44 is noted at one or more staticgap distances S which are observed from the scale 46 of the micrometer42.

DYNAMroTEs'r ASSEMBLY Referring to FIGS. 3-6, the dynamic test assembly30 typically comprises, in general, a plate member 48 having a verticalaxis 50 and swash-surface 52; carrier means 54 for supporting the pickup18 abovethe swashsurface 52; horizontal adjustment means 56 forvmovingthe carn'er means 54 horizontally to position the sensing tip 16 of thepickup 18 accurately at a selected location along a radius (not visible)of the swash-surface 52; and drive means 58 including speed adjustmentmeans 60 for rotat ing plate member 48 at a selected velocity.

Referring to FIG. 6, the swashsurface S2 is inclined relative to areference plane 62 extending normal' to the vertical axis 5l). Theswashsurface 52 intersects the reference plane 62 along a line 63(normal to the plane of the drawing) which intersects the vertical axis50. The overall arrangement is such that as the plate. men ber 48 isrotated, that region of the swashsurface 52 directly beneath the sensingtip 16 approaches toward and recede's from the sensing tip 16 tosimulate a vibrat ing metallic body. At any distance R from thevertical' axis 50, the amount of vertical displacement of theswashsurface 52 vdirectlybeneath the sensing tip 16 is known.

Referring to FIGS. 3-5, the horizontal adjustment means 56 comprises astationary block 64 and a mounting block 66 connected to the stationaryblock 64 by a dovetail slide connection 68. A threaded shaft 70 isengaged in a threaded bore 72 provided in the mounting block 66. 'Dieshaft 70 is rotated by a knob 74 secured thereto.

Referring to FIG. 3, the upper surface of the stationary block 64 isprovided with a plate 76 having a graduated displacement scale 77. Thetop surface of n mounting block 66 is provided with transparent plate.18 having an indicator line 79. The scale 77 and indicator line 79 Acooperate to indicate the amount of vertical displacement of theswash-surface 52 above and.below the reference. plane' 62 (FIG. 6),7 atselecteddistances R from the vertical axis 50.

The drive means 58 comprises a high spd electric rnotor 80 supportedbelow the top wall .36 by a mounting ring 82. The plate member 48 issecured to a drive shaft 75 L1. 84 of the motor 80 and is therebysupported for rotation about the vertical axis 50. The plate member 48resides within an opening 86 formed in the top wall 36 and is presentedopposite to the sensing tip 16 of the'pickup 18.

The speed control means' 60 includes a speed indicator knob 87 and anon-off switch 88.

PRESENT INVENTION The present improvement resides in gap distanceadjustment means for moving the pickup 18 vertically to position thesensing tip 16 thereof accurately at a predetermined distance from thereference plane 62.

Referring to FIGS. 3 and S, the carrier' means 54 comprises an arm 90having a central opening 92 receiving the split body adapter bushing 39.The arm 98 has a slot 94 and` a clamping screw 96 which cooperate tofrictionally clarnpthe adapter b ushing 39 within the central opening92.

The arm 90 is connected to the mounting block 66 by the gap distanceadjustment means 98 of this invention. As best shown in FIG. 3, the gapdistance adjustment means 98 comprisesa dovetail rib 100 formed in thearm 90 and a complementary groove 102 formed in the mounting block 66.As best shown in FIG. 5, a'threaded shaft 104 is engaged in a threadedbore 106` provided in the rib 100. The threaded shaft 104 is rotated bya knob'108 secured thereto.

OPERATION ncfcvring to Pros. 5 and 6, the output vonage of u pickup 18per unit of displacement of the swashsurfaca 52 ata known gap distance Scan be accurately determined l asl follows. The arm 90 is movedhorizontally by rotation of the knob 74 to position thepickup 18 at aselected position, as indicated by the graduated displacement scale 77and the indicator line 79, relative to the swash-surface 52. The platemember is rotated at a selected speed. With the voltmeter switch in theD.C. position, the D.C. value of the output voltage of the pickup 18 isindicated on the voltmeter 44. Theuknob 108 of the vertical adjustmentmeans 98 is rotated in the appropriate. direction to raise or lower thepickup 18 until the voltmeter 44 indicates a D.C output voltage Vocorresponding to the known gap distance S. While the plate member 48 isrotating, the voltmeter 44 is switched to A.C. and indicates thepeak-topeak voltage designated Vp' (FIG. 6). The peak-topeak voltage Vpis divided by the deviation of the swash-surface 52 to determine thedesired output voltage per unit of displacement from the static gapdistance S. This operation may be repeated at other static gapdistances.

The gap distance adjustment means 98 of this invention permits accurateplacement of the sensing tip of a pickup -at a desired static gapdistance. The output voltage c haracteristic of the pickup thus may beaccurately determined at a known static gap distance.

I claim:

l. In a test unit for non-contact pickups, said test unit u comprising aplate member having a rotation axis and a swash-surface which isinclined relative to a reference plane. extending normal to saidrotation axis; said refer ence plane intersecting said swashsurfacealong a line which intersects said Irotation axis; means for supponingsaid plate member for4 rotation about said rotation axis; a non-contactpickup having a sensing tip; mounting means supporting said non-contactpickup spaced-apart from said swash-surface; transverse adjustment meanssupporting said mounting means for movement transversely to positionsaid sensing tip accurately at a selected location along a radius ofsaid swasheurface; and drive means for rotating said plate member; theimprovement comprising: s

gap distance adjustment means for moving said pickup parallel to saidrotation axis to position said sensing tip accurately at a predetennineddistance from said reference plane.

3. The improvement defined in claim l wherein said gap 5 RUDOLPH v'ROLINEC Pnmary Ema" l: dism adjustment means comprises a threaded shanR- J. CORCORAN. Assistant Eranner carried by said transverse adjustmentmears and threadily A engaged with said mounting means, said threadedshaft Us' CL X3- extending parallel with said rotationaxis. w I3-l,71.4; 307-195; 323.31;

, 6 2. The improvement defined in claim 1 wherein said Y Reim (3M s gapdistance adjustment means is interposed between said mounting means andsaid transverse adjustment UNITED STATES PATENTS

